In original photography it is possible to control the exposure of the camera original, but not with the degree of precision that is desired. It has therefore been the practice of the motion picture film industry to undertake a color analysis or "timing" of the film, and make appropriate adjustments of the color and intensity balance before preparing release prints. The initial timing of the film requires the qualitative judgment of a qualified person, but some subsequent processing steps can be performed automatically by means of appropriate equipment.
More specifically, a typical motion picture includes a sequence of separate scenes, with each scene having a duration from a few seconds to about a minute or more. It therefore requires a number of frames of the original film to depict each scene. The lighting conditions for each scene remain substantially constant throughout that particular scene. It has therefore been the practice in the "timing" of original film to view one or more frames of each scene, determine the appropriate color corrections for that frame which will then be also applied to all of the other frames of that scene, and then go to a frame of the next succeeding scene.
According to presently established technology the overall process of determining the color corrections and incorporating them into the release prints involves three separate phases. In the first phase the original film is reviewed by a qualified person who determines what the color corrections should be and records information indicating the magnitude of such corrections.
In the second phase of the process an appropriate duplicate of the original film is printed from the original film, and the previously recorded information indicating the color corrections to be made in the frames of each scene are effected by use of automatic equipment. Specifically, a variable light source is used in which light beams of three primary colors are formed separately and are then combined into a composite light beam, and automatic means responding to the previously recorded information varies the intensity of the primary color light beams so as to thereby vary both the intensity and the chroma, or color characteristic, of the composite beam. It will therefore be understood that the duplicate original film, though duplicating the picture information obtained in the original photography, nevertheless incorporates an adjusted or refined version of the colorimetric information.
The third phase of processing in accordance with present technology is quite straightforward. The duplicate original film is fed to a high speed printer for printing whatever number of release prints are desired. Since necessary corrections had been made previously, this is a straightforward printing or copying operation.
The present invention is not directed to either the second phase or the third phase of the conventional process, but is directed only to the first phase of that process. According to the present invention the objective of the first phase of the process remains the same, but the specific technique or steps, and the equipment used to carry them out, are significantly different.
Therefore, the object and purpose of the present invention is to provide an improved method and apparatus for performing a subjective colorimetric evaluation of photographic film, and for recording the information obtained from such evaluation.